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2020 National Emissions Inventory Technical
Support Document: Solvents - All Other
Solvents
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EPA-454/R-23-001ff
March 2023
2020 National Emissions Inventory Technical Support Document: Solvents - All Other Solvents
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC
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Contents
List of Tables i
32 Solvents - All Other Solvents 32-1
32.1 Sector Descriptions and Overview 32-1
32.2 EPA-developed estimates 32-3
32.2.1 Activity and Allocation Data 32-3
32.2.2 Emission Factors 32-5
32.2.3 Controls 32-8
32.2.4 Emissions 32-11
32.2.5 Point Source Subtraction 32-12
32.2.6 Sample Calculations 32-12
32.2.7 Improvements/Changes in the 2020 NEI 32-12
32.2.8 Puerto Rico and U.S. Virgin Islands 32-13
32.3 References 32-13
List of Tables
Table 32-1: Nonpoint solvent SCCs in the 2020 NEI 32-1
Table 32-2: Source Categories That Use Population Activity Data 32-3
Table 32-3: Source Categories That Use Employment Activity Data 32-4
Table 32-4: Fraction of application assumed to occur indoors per SCC 32-7
Table 32-5: Post-use control assumptions and emission factor inflation percentages 32-9
Table 32-6: States with area source VOC rules relevant to the solvent sector 32-11
Table 32-7: Sample calculations for All Adhesives and Sealants 32-12
l
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32 Solvents - All Other Solvents
32.1 Sector Descriptions and Overview
The solvent sector is a diverse collection of residential, commercial, institutional, and industrial sources
of gas-phase organic emissions. Included in this sector are everyday items, such as cleaners, personal
care products, adhesives, coatings, printing inks, and pesticides. These sources generate emissions
through evaporative processes and include organics that fulfill product functions beyond acting as a
traditional solvent (e.g., propellants, fragrances). As such, this sector is often described as the volatile
chemical product (VCP) sector.
For the 2017 NEI, the magnitude of VOC emission estimates for this sector were largely based on
national-level solvent usage reported by the Freedonia Group [ref 1], The reader is referred to the 2017
TSD for more information on those methods. For the 2020 NEI, EPA has adopted emission factors
generated using a new framework for most of this sector [ref 2],
The 2020 NEI added one new SCC to this sector (2460030999). In addition, emissions from agricultural
pesticides (2461850000) are estimated using the new methodology. The table below notes all SCCs
covered in this source category and the SCCs for which the EPA generates default emissions.
Table 32-1: Nonpoint solvent SCCs
SCC
SCC Level 1
SCC Level 2
SCC Level 3
SCC Level 4
EPA
2401001000
Solvent
Utilization
Surface Coating
Architectural Coatings
Total: All Solvent
Types
X
2401005000
Solvent
Utilization
Surface Coating
Auto Refinishing
Total: All Solvent
Types
X
2401008000
Solvent
Utilization
Surface Coating
Traffic Markings
Total: All Solvent
Types
X
2401015000
Solvent
Utilization
Surface Coating
Factory Finished Wood
Total: All Solvent
Types
X
2401020000
Solvent
Utilization
Surface Coating
Wood Furniture
Total: All Solvent
Types
X
2401025000
Solvent
Utilization
Surface Coating
Metal Furniture
Total: All Solvent
Types
X
2401030000
Solvent
Utilization
Surface Coating
Paper
Total: All Solvent
Types
X
2401040000
Solvent
Utilization
Surface Coating
Metal Cans
Total: All Solvent
Types
X
2401055000
Solvent
Utilization
Surface Coating
Machinery and
Equipment
Total: All Solvent
Types
X
2401060000
Solvent
Utilization
Surface Coating
Large Appliances
Total: All Solvent
Types
X
32-1
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see
see Level 1
SCC Level 2
SCC Level 3
SCC Level 4
EPA
2401065000
Solvent
Utilization
Surface Coating
Electronics and Other
Electrical
Total: All Solvent
Types
X
2401070000
Solvent
Utilization
Surface Coating
Motor Vehicles
Total: All Solvent
Types
X
2401075000
Solvent
Utilization
Surface Coating
Aircraft
Total: All Solvent
Types
X
2401085000
Solvent
Utilization
Surface Coating
Railroad
Total: All Solvent
Types
X
2401080000
Solvent
Utilization
Surface Coating
Marine
Total: All Solvent
Types
X
2401090000
Solvent
Utilization
Surface Coating
Misc. Manufacturing
Total: All Solvent
Types
X
2401100000
Solvent
Utilization
Surface Coating
Industrial Maintenance
Coatings
Total: All Solvent
Types
X
2401200000
Solvent
Utilization
Surface Coating
Other Special Purpose
Coatings
Total: All Solvent
Types
X
2415000000
Solvent
Utilization
Degreasing
All Processes/All
Industries
Total: All Solvent
Types
X
2425000000
Solvent
Utilization
Graphic Arts
All Processes
Total: All Solvent
Types
X
2460100000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All Personal Care
Products
Total: All Solvent
Types
X
2460200000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All Household Products
Total: All Solvent
Types
X
2460400000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All Automotive
Aftermarket Products
Total: All Solvent
Types
X
2460600000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All Adhesives and
Sealants
Total: All Solvent
Types
X
2460800000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All FIFRA Related
Products
Total: All Solvent
Types
X
2460500000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
All Coatings and
Related Products
Total: All Solvent
Types
X
2461850000
Solvent
Utilization
Miscellaneous Non-
industrial: Commercial
Pesticide Application:
Agricultural
All Processes
X
2460900000
Solvent
Utilization
Misc. Non-industrial:
Consumer and Commercial
Misc. Products
Total: All Solvent
Types
X
32-2
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32.2 EPA-developed estimates
Solvent utilization emissions are largely based on estimates of national-level usage and allocated to the
county-level using more geographically specific sources of data. Product usage of each SCC is
preferentially estimated using economic statistics from the U.S. Census Bureau's Annual Survey of
Manufacturers, commodity prices from the U.S. Department of Transportation's 2012 Commodity Flow
Survey and the U.S. Census Bureau's Paint and Allied Products Survey, and producer price indices, which
scale commodity prices (e.g., 2012) to target years (e.g., 2020) and are retrieved from the Federal
Reserve Bank of St. Louis. If any of the datasets are unavailable, default usage estimates will be derived
using functional solvent usage statistics reported by The Freedonia Group or sales quantities reported in
a California Air Resources Board (CARB) California-specific survey [ref 3], The composition of products
will be estimated by generating composites from CARB surveys [refs 4,5,6,7,8] and profiles reported in
the U.S. EPA's SPECIATE database [ref 9], Emissions are subsequently estimated using a framework that
considers product composition, timescales of product usage, and timescales of evaporation for
individual components [ref 2],
In the following sections, details are provided related to the collection of activity data, allocation of
national-level emission estimates to the county-level, calculation of emission factors, calculation of
emissions, state-specific variations in emission factors due to assumed nonpoint VOC controls and point
source subtraction.
32.2.1 Activity and Allocation Data
Activity data for solvent utilization is SCC-specific. For most SCCs, activity data is based on year-specific
county-level population or employment data from the U.S. Census Bureau. Exceptions include county-
level use estimates of active ingredients in agricultural pesticides from the United States Geological
Survey [ref 10] (2461850000) and vehicular lane miles traveled on paved roads from the Federal
Highway Administration [ref 11] and MOVES model (2401008000). All activity data reflects the most
recently available dataset.
The eleven SCCs allocated from the national-level to the county-level using population are listed in the
table below.
Table 32-2: Source Categories That Use Population Activity Data
SCC
Description
2401001000
Architectural Coatings
2401100000
Industrial Maintenance Coatings
2401200000
Other Special Purpose Coatings
2460100000
All Personal Care Products
2460200000
All Household Products
2460400000
All Automotive Aftermarket Products
2460600000
All Adhesives and Sealants
2460800000
All FIFRA Related Products
2460500000
All Coatings and Related Products
32-3
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see
Description
2460900000
Misc. Products
2460030999
Lighter Fluid, Fire Starter, Other Fuels
The SCCs allocated from the national-level to the county-level using employment statistics from the U.S.
Census Bureau's County Business Patterns are all typically industrial in nature and listed in the table below.
Table 32-3: Source Categories That Use Employment Activity Data
see
Description
NAICS
2401005000
Auto Refinishing
81112/, 4411//, 4412//
2401015000
Factory Finished Wood
321///
2401020000
Wood Furniture
337110, 337121, 337122, 337127*, 337211, 337212,
337215*
2401025000
Metal Furniture
337124, 337127*, 337214, 337215*
2401030000
Paper
322220
2401040000
Metal Cans
33243/
2401055000
Machinery and Equipment
333///
2401060000
Large Appliances
3352//
2401065000
Electronics and Other Electrical
331318, 3314//, 33592/, 335311
2401070000
Motor Vehicles
3361//, 3362//, 3363//, 3369//
2401075000
Aircraft
3364//
2401085000
Railroad
3365//
2401080000
Marine
3366//
2401090000
Misc. Manufacturing
339///
2415000000
Degreasing: All Processes/All
Industrial
331 ///, 332III, 333//I, 334///, 335///, 336///,
337//I, 339///, 441///, 483///, 484///, 485///,
2425000000
Graphic Arts
32311/, 32221/, 32222/, 32223/, 322299
2420000000
Dry Cleaning
812320
* Employment data is split evenly between Wood Furniture and Metal Furniture
Emissions from agricultural pesticides (2461850000) are allocated from the national-level to the county-
level using active ingredient application statistics from the United States Geological Survey. These
statistics are reported at the county-level and the EPEST_HIGH_KG value in the associated dataset is
utilized. The most recent dataset available is from 2017, and is used for the 2020 NEI. Due to data
limitations, the USGS statistics do not contain active ingredient usage statistics for Alaska and Hawaii.
For these jurisdictions, the mass of active ingredients applied in the conterminous United States was
summed and divided by the total acres treated with pesticides, insecticide, and fungicide in the
conterminous United States, as reported by the United States Department of Agriculture's Census of
Agriculture [ref 12]. These usage factors (kg pesticide active ingredient usage per acre treated) were
32-4
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then applied to the Census of Agriculture's reporting of total acres treated per-county in Alaska and
Hawaii.
Emissions from traffic markings (2401008000) were previously allocated from the national-level to the
state-level using data from the U.S. Department of Transportation's Federal Highway Administration,
and from the state-level to the county-level using population data. For the 2020 NEI and beyond,
national-level allocation methods for traffic markings utilize estimates of county-level paved vehicular
miles traveled, which is consistent with the methods employed for asphalt paving. This update assumes
application of traffic markings is correlated with pavement of roads.
Due to confidential business information concerns, the U.S. Census Bureau often withholds data in the
County Business Patterns dataset. This is the case if a particular county has 2 or fewer establishments
under a given North American Industrial Classification Standard (NAICS) code. In prior years, the County
Business Patterns data reported the counties where data was withheld, along with dataset ranges for
the withheld data (e.g., 20-99 employees). A gap-filling procedure was implemented using state-level
data, which did not feature withheld data, to estimate employment counts in all counties.
Beginning in 2018, the Census Bureau stopped reporting dataset ranges for counties with withheld data.
As such, the prior gap-filling methods required updating. For all post-2017 inventories, year-specific
employment data from the County Business Patterns dataset is used to determine the total amount of
withheld data in each state. The 2017 version of the County Business Patterns is then used to determine
the counties for which withheld data exist and the data ranges for those counties, and it is to these
counties that the difference between the state-level total employment and county-level total
employment are allocated.
32.2.2 Emission Factors
Emissions factors are provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEI
Supporting Data and Summaries site.
The framework [ref 2] used to estimate emission factors from the nonpoint solvent sector considers:
1. The mass of chemical products used,
2. The composition of these chemical products,
3. The physiochemical properties of the chemical product constituents that govern volatilization,
and
4. The timescale available for these constituents to evaporate.
This methodology resolves several issues in prior methods. First, prior methods did not account for fate-
and-transport. Often, chemical products (e.g., personal care products) are quickly sequestered and thus
unavailable for emission. Therefore, the speciation and magnitude of organics in emissions can differ
from the speciation and magnitude of organics in the composition of products from which they
volatilize. To consider fate-and-transport, the new methodology accounts for the evaporation timescale
of the individual components within products and the use timescale available for evaporation (i.e., the
elapsed time between application and any explicit removal process). Second, prior methods only
quantified mass usage of chemicals that function as solvents. Sources in this sector include organics that
evaporate and fulfill product functions beyond acting as a traditional solvent (e.g., isobutane as
propellants, monoterpenes as fragrances). The new methodology attempts to quantify all organic mass
32-5
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that evaporates on relevant timescales. Third, prior methods assumed all mass usage and subsequent
evaporation consisted of organics classified as regulatory VOCs. Evaporative organics from chemical
products include many organics that are exempt compounds (e.g., acetone, siloxanes) and their
proportions much be accounted for to accurately estimate regulatory VOC emissions.
Sector-relevant usage estimates are based on national-level data, including data from the U.S. Census
Bureau's Annual Survey of Manufacturers, commodity prices from the U.S. Department of
Transportation's 2012 Commodity Flow Survey and the U.S. Census Bureau's Paint and Allied Products
Survey, and producer price indices from the Federal Reserve Bank of St. Louis. Derivation of product
usage is as follows:
„_(S xlOOO)/ (1)
/(«> x JxP„P)
Where:
U = Annual usage in kg person"1 year"1.
5 = Annual Survey of Manufacturers shipment value in $1000 year"1.
CP = Commodity Price from the U.S. Department of Transportation's 2012 Commodity
Flow Survey or the U.S. Census Bureau's Paint and Allied Products Survey in kg year"
i
PPI2020 = Producer Price Index from the Federal Reserve Bank of St. Louis for the appropriate
NAICS code in 2019 (unitless).
PPIX = Producer Price Index from the Federal Reserve Bank of St. Louis for the appropriate
NAICS code in "Price Year" (unitless).
Pop = National-level population count from the U.S. Census Bureau.
Due to data limitations, usage estimates for three SCCs follow different methods. Miscellaneous
products (2460900000) and lighter fluid (2460030999) usage estimates are retrieved from sales
quantities reported in a California-specific survey [ref 3], and dry-cleaning (2420000000) usage
estimates are retrieved from a report published by The Freedonia Group [ref 1],
To translate from usage to emissions, fate-and-transport is considered. Here, fate-and-transport is a
function of the predicted evaporation timescale of each compound and the assigned use timescale of
each product category. The evaporation timescale is the compound specific, characteristic timescale of
emission from a surface layer and is calculated using previously published methods [ref 13,14], This
timescale is defined as a relationship between the mass of a compound applied and the rate of its
emission, which can be expressed by:
Evaporation Time scale [hr] = ^aPPliedj =^OAxdj^ (2
/ nemission e
Where:
Koa = The octanol-air partitioning coefficient of the compound.
d = The assumed depth of the applied product layer.
Me = The mass transfer coefficient of the compound from the surface layer into the bulk
air, which is a function of aerodynamic and boundary layer resistances.
32-6
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A compound's K0a it is the ratio of an organic chemical's concentration in octanol to the organic
chemical's concentration in air at equilibrium. It is often used to quantify the partitioning behavior of an
organic compound between air and a matrix. As experimental values of KOA are sparse, modeled
estimates from the QSAR model OPERA [ref 15] are used and are retrieved from the U.S. EPA's CompTox
Chemistry Dashboard. In addition, each product category is assigned an indoor usage fraction (see Table
below). This assignment enables the mass transfer coefficient to vary between indoor and outdoor
conditions. Typically, the mass transfer coefficent indoors is smaller than the mass transfer coefficient
outdoors due to more stagnant atmospheric conditions, and the newest version of the modeling
framework reflects these dynamics. Indoor product usage utilizes a ve of 5 m hr1, and the remaining
outdoor portion is assigned a ve of 30 m/hr [ref 13,14], Median values for d [0.1 mm] from Khare and
Gentner (2018) [ref 13] are applied for both indoors and outdoors.
Ta
lie 32-4: Fraction of application assumed to occur indoors per SCC.
see
Description
Assumed Indoor Emission [fraction]
2401001000
Architectural Coatings
0.50
2401005000
Auto Refinishing
0.50
2401008000
Traffic Markings
0.50
2401015000
Factory Finished Wood
0.50
2401020000
Wood Furniture
0.50
2401025000
Metal Furniture
0.50
2401030000
Paper
0.50
2401040000
Metal Cans
0.50
2401055000
Machinery and Equipment
0.50
2401060000
Large Appliances
0.50
2401065000
Electronic and Other Electrical
0.50
2401070000
Motor Vehicles
0.50
2401075000
Aircraft
0.50
2401085000
Railroad
0.50
2401080000
Marine
0.50
2401090000
Misc. Manufacturing
0.50
2401100000
Industrial Maintenance Coatings
0.50
2401200000
Other Special Purpose Coatings
0.50
2415000000
Degreasing: All Processes/All Industries
1.00
2425000000
Graphic Arts
0.50
2460100000
All Personal Care Products
*
2460200000
All Household Products
1.00
2460400000
All Automotive Aftermarket Products
0.00
2460600000
All Adhesives and Sealants
1.00
2460800000
All FIFRA Related Products
0.00
2460500000
All Coatings and Related Products
0.50
2461850000
Agriculture Pesticides
0.00
2460900000
Misc. Products
1.00
2420000000
Dry Cleaning
0.50
32-7
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see
Description
Assumed Indoor Emission [fraction]
2460030999
Lighter Fluid, Fire Starter, Other Fuels
0.00
* Emissions for Personal Care Products are calculated separately for short-use products and daily-use products.
The final emission factor reflects a summation of both emission categories. Within the emissions modeling, a
1.00 indoor emission fraction is assumed for short-use products and a 0.50 indoor emission fraction is assumed
for daily-use products.
Emissions are then determined by comparing the calculated evaporation timescale for each component
with the assigned use timescale for the product category from which the component resides. The use
timescale is the timescale available for a product category to evaporate and is based on the length of its
direct use phase. If the use timescale for the product category is greater than the evaporation timescale
of an organic ingredient, the compound is assumed to be emitted. Else, the compound is assumed to be
retained in the product or other condensed phase and permanently sequestered. Overall, organic
emissions (E) for the complete sector are calculated as a summation over all organic compounds, /', and
product categories,/, as follows:
= 1
fO if Use Time scalej < Evaporation Time scale;
[£/,¦ X fE] x fs.. x (l ~ fcj) if Use Time scale j > Evaporation Time scale i
(3)
Where:
U
U
fs
category,
fc
= Product usage.
= Evaporative organic fraction
= Fraction of an organic compound in the evaporative organics portion of a product
= Fraction of emissions that feature post-use controls on a mass basis.
32.2.3 Controls
There are two methods for controlling organic emissions from the nonpoint solvent utilization sector.
The first method involves product reformulation, where existing VOC ingredients are substituted with
exempt organic compounds (e.g., acetone) or the VOC mass content of products is lowered. Regulations
are often set to limit the VOC content of chemical products, with California typically setting the most
stringent limits in the country [ref 17], To reflect local regulations, the 2017 NEI made additional
reductions to consumer solvent, architectural coating, and industrial maintenance coating SCCs for
several states. The consumer solvent reductions were calculated using a phased approach developed in
an Ozone Transport Commission (OTC) report where each marginal reduction reflect fractional changes
to California Air Resource Board's (ARB) VOC inventory for consumer products. As ARB's most recent
consumer and commercial product survey, which reports the VOC content and composition of products,
is used in the underlying methodology, the fractional reductions to consumer products through product
reformulation over time are implicitly captured. Therefore, it is assumed that these phased controls are
represented, and further reductions are not necessary. However, application of emission factors whose
derivation use the VOC content and composition of products from ARB's most recent survey to all states
would artificially reduce emissions where area source VOC rules relevant to the solvent sector have not
been adopted.
32-8
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To account for emission variations for relevant consumer solvent SCCs, supplemental data from the OTC
report are paired with information from ARB's most recent survey to quantify the VOC content of
products prior to rule adoption. These pre-rule VOC content values are then used to generate emission
factor multipliers for relevant SCCs and have been applied to generate the relevant emission factors for
this sector. For example, ARB's most recent survey reports 10.14 tons per day of Brake Cleaner sales.
The OTC documentation reports a 3.7 tons per day reduction in VOC emissions due to the adoption of a
VOC limit of 10%, by weight. Therefore, the VOC limit prior to the rule adoption was 46.5%, by weight,
which is derived using the following equation:
Pvocr —
S X {VOC,
wt%i
yocwt%/)
(i)
Where:
PvOCr
S
VOCwt%i
VOCwt%f
Daily VOC emission reduction for a given product.
Daily sales of a given product.
Initial VOC weight %.
Final VOC weight %.
Similar VOC content updates were applied to multipurpose solvents, paint thinners, disinfectants, floor
polish, windshield washer fluids, construction adhesives, and all other products considered in the OTC
documentation [ref 16]. The updated VOC content values for all listed products were then applied to the
derivation of the VOC content for all relevant product categories in the new emissions framework.
Following this procedure, products are aggregated into relevant categories (e.g., household cleaners)
and emission factor multipliers were generated (see table below).
Table 32-5: Post-use control assumptions and emission factor inflation percentages.
Post-Use Control
Emission Factor
see
Description
Assumption
Multiplier for
[fraction]
Uncontrolled States
2401001000
Architectural Coatings
0.00
1.340
2401005000
Auto Refinishing
0.00
-
2401008000
Traffic Markings
0.00
-
2401015000
Factory Finished Wood
0.00
-
2401020000
Wood Furniture
0.00
-
2401025000
Metal Furniture
0.00
-
2401030000
Paper
0.00
-
2401040000
Metal Cans
0.00
-
2401055000
Machinery and Equipment
0.00
-
2401060000
Large Appliances
0.00
-
2401065000
Electronic and Other Electrical
0.00
-
2401070000
Motor Vehicles
0.00
-
2401075000
Aircraft
0.00
-
2401085000
Railroad
0.00
-
2401080000
Marine
0.00
-
32-9
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see
Description
Post-Use Control
Assumption
[fraction]
Emission Factor
Multiplier for
Uncontrolled States
2401090000
Misc. Manufacturing
0.00
-
2401100000
Industrial Maintenance Coatings
0.00
1.340
2401200000
Other Special Purpose Coatings
0.00
-
2415000000
Degreasing: All Processes/All
Industries
0.00
—
2425000000
Graphic Arts
0.00
-
2460100000
All Personal Care Products
0.00
1.003
2460200000
All Household Products
0.00
1.079
2460400000
All Automotive Aftermarket
Products
0.00
3.548
2460600000
All Adhesives and Sealants
0.00
1.380
2460800000
All FIFRA Related Products
0.00
-
2460500000
All Coatings and Related Products
*
2.025
2461850000
Agriculture Pesticides
0.00
-
2460900000
Misc. Products
0.00
-
2420000000
Dry Cleaning
0.00
-
2460030999
Lighter Fluid, Fire Starter, Other
Fuels
0.90**
—
* Emissions for All Coating and Related Products are calculated separately for aerosol coatings and allied paint
products (e.g., paint thinners, clean up solvents, multipurpose solvents, etc.). The final emission factor reflects a
summation of both emission categories. Within the emissions modeling, a 0.33 post-use control factor is applied
to allied paint products to reflect disposal of clean up solvents and paint thinners.
** Emissions for Lighter Fluid, Fire Starter, Other Fuels are assumed to feature 90% destruction via in-use
combustion.
Uncontrolled emission factors for architectural coatings and industrial maintenance coatings are
quantified using the prior ratio of controlled to uncontrolled emissions, which were based on estimates
from the Eastern Regional Technical Advisory Committee. In the 2017 NEI, architectural and industrial
maintenance coatings generated 2.03 lb/capita in states with applicable area source VOC rules and 2.72
lb/capita in states without rules. The resulting 1.340 scaling factor (2.72 / 2.03) is used to generate the
uncontrolled emission factor shown above.
The second pathway for controlling organic emissions from the solvent utilization sector involves post-
use controls. These methods include add-on controls, manufacturing process modifications, and disposal
techniques. A post-use control assumption is applied in the derivation of two SCCs: 2460500000 and
2460030999 (see table above). Since adoption of additional post-use control technologies vary widely in
space and time, assigning blanket post-use controls beyond these two SCCs is not considered here. In
lieu of these blanket assumptions, the Solvent Tool allows users to adjust emissions factors to account
for controls, if needed.
The states for which area source VOC rules and controlled emissions factors will be applied are shown
below.
32-10
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Table 32-6: States with area source VOC rules relevant to the solvent sector.
State
Consumer
Solvents
Architectural /Industrial
Maintenance Coatings
AZ
X
CA
X
X
CO
X
X
CT
X
X
DE
X
X
DC
X
X
ME
X
X
MD
X
X
MA
X
X
NH
X
X
NJ
X
X
NY
X
X
PA
X
X
Rl
X
X
TX
X
UT
X
X
VT
X
VA
X
X
32.2.4 Emissions
Total VOC emissions from solvent utilization are calculated by multiplying the activity data for the source
category by the calculated emissions factor for that category.
Evocc,s = Ac,s x EFvoc,s (1)
Where:
Evoc,c,s = Annual VOC emissions in county c for source category s, in tons per year.
Ac,s = Activity data for county c associated with source category s.
EFvoqs = Calculated VOC emissions factor for source category s.
Speciation factors for these sources are provided on the 2020 NEI Supporting Data and Summaries site.
HAP emissionss are estimated using the VOC emissions and HAP speciation factors. This step is
completed after the point source subtraction step discussed in section H. It should be noted that if a
speciation profile normalized to Total Organic Gas (TOG) is used for HAP-augmentation, the TOG/VOC
ratio must first be applied to the Speciation Factor.
Ep,c,s Evoc,c,s ^ SFp s (13)
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Where:
Ep,c,s = Annual emissions of HAP p county c for source category s, in tons per year.
Evoc,c,s = Annual VOC emissions in county c for source category s, in tons per year.
5Fp,s = Speciation factor for HAP p for source category s.
32.2.5 Point Source Subtraction
Since emissions from solvent utilization occur from both point and nonpoint SCCs, point source
subtraction is required to ensure emissions from this sector are not double-counted. To accomplish this
task, nonpoint SCCs must be mapped to corresponding point SCCs. This crosswalk can be found on the
Nonpoint Methods Advisory (NOMAD) Sharepoint.
Point source subtraction for this sector should be completed at the county level using uncontrolled point
source emissions. As such, assumptions related to the control efficiency of the point sources must be
made. Often, the point source emission estimates submitted to the NEI feature 80-90% control
efficiencies. Uncontrolled point source emission calculations will be calculated, as necessary, using the
submitted point source emissions, engineering judgement, and an assumed control efficiency.
The net calculation of nonpoint emissions following point source subtraction is as follows:
NPs,c = TES C X PSsc (2)
Where:
NPs,c = Nonpoint source solvent emissions in county c for source category s, in tons per year.
TEs,c = Total solvent emissions s in county c for source category s, in tons per year.
PSs,c = Point source solvent emissions in county c for source category s, in tons per year.
If point source subtraction results in negative emissions, the Solvent Tool will zero out emissions for that
source category in that county. HAP emissions are speciated from the estimated nonpoint source VOC
emissions following point source subtraction.
32.2.6 Sample Calculations
Sample calculations for VOC emissions from adhesives and sealants solvent utilization are included in
the table below. The values in these equations are demonstrating program logic and are not
representative of any specific NEI year or county.
Table 32-7: Sample calculations for All Adhesives and Sealants
Eq. #
Equation
Values
Result
5
E-c = E P.scc x Pc
L84 W/capita x 66<000 Veople
60.72 tons of
VOC
32.2.7 Improvements/Changes in the 2020 NEI
Substantial methodological changes to estimate emissions from this sector was made for the 2020 NEI.
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The reader is directed to the previously cited reference [ref 2] for additional details on the emission
factor generation methods. In addition, agricultural pesticide (2461850000) emissions are now
generated using the updated methods and are not estimated via a separate tool.
32.2.8 Puerto Rico and U.S. Virgin Islands
For all SCCs that utilize population and employment statistics, emissions from Puerto Rico and the U.S.
Virgin Islands are calculated using the same methodology described above. For agricultural pesticides
and traffic markings, emissions are estimated using per-capita activity data from representative counties
in Florida (Broward County and Monroe County for Puerto Rico and the U.S. Virgin Islands, respectively).
32.3 References
1. The Freedonia Group: Solvents, Industry Study #3429, The Freedonia Group, Cleveland, OH,
2016.
2. Seltzer, K. M., Pennington, E., Rao, V., Murphy, B. N., Strum, M., Isaacs, K. K., and Pye, H. O. T.:
Reactive organic carbon emissions from volatile chemical products, Atmos. Chem. Phys., 21,
5079-5100, https://doi.org/10.5194/acp-21-5079-2021, 2021. Note: emissions model is
available and updated at https://github.com/USEPA/VCPy.
3. California Air Resources Board (CARB): Final 2015 Consumer & Commercial Product Survey Data
Summaries, 2019.
4. U.S. Environmental Protection Agency: Final Report, SPECIATE Version 5.0, Database
Development Documentation, Research Triangle Park, NC, EPA/600/R-19/988, 2019.
5. Wieben, C.M., 2019, Estimated Annual Agricultural Pesticide Use for Counties of the
Conterminous United States, 2013-17 (ver. 2.0, May 2020): U.S. Geological Survey data release,
https://doi.org/10.5066/P9F2SRYH.
6. U.S. Department of Transportation, Federal Highway Administration, Office of Highway Policy
Information; Table HM-51 - Highway Statistics 2018.
7. U.S. Department of Agriculture, 2012 Census of Agriculture, Volume 1- Part 51; AC-12-A-51.
8. Khare, P. and Gentner, D. R.: Considering the future of anthropogenic gas-phase organic
compound emissions and the increasing influence of non-combustion sources on urban air
quality, Atmos. Chem. Phys., 18, 5391-5413, https://doi.org/10.5194/acp-18-5391-2018, 2018.
9. Weschler, C. J. and Nazaroff, W. W.: Semivolatile organic compounds in indoor environments,
Atmos. Environ., 42, 9018-9040, 2008.
10. Mansouri, K., Grulke, C. M., Judson, R. S., and Williams, A. J.: OPERA models for predicting
physicochemical properties and environmental fate endpoints, J. Cheminformatics, 10, 10,
https://doi.org/10.1186/sl3321-018-0263-l, 2018.
11. U.S. Environmental Protection Agency: Emission Inventory Improvement Program, Auto Body
Refinishing, Volume III: Chapter 13, January 2000.
12. Ozone Transport Commission: OTC Model Regulations for Nitrogen Oxides (NOx) and Photo-
reactive Volatile Organic Compounds (VOCs), Technical Support Document, Ozone Transport
Commission, Boston, MA, 2016.
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United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-23-001ff
Environmental Protection Air Quality Assessment Division March 2023
Agency Research Triangle Park, NC
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